The present invention relates to a method of assembling a valve module of a fuel injector.
U.S. Pat. No. 4,946,107 has already described an electromagnetically operable fuel injector having, inter alia, a nonmagnetic sleeve as the connecting part between a core and a valve valve seating body. The sleeve runs over its entire axial length with a constant outside diameter and a constant inside diameter and accordingly has equally large inlet openings at both ends. The core and the valve seating body are designed with an outside diameter such that they extend into the sleeve at both ends so that the sleeve completely surrounds both parts, the core and the valve seating body, in areas projecting into them. A valve needle with an armature that is guided through the sleeve moves inside the sleeve. The fixed connections of the sleeve to the core and the valve seating body are achieved by welding, for example, as is also described in German Published Patent Application No. 43 10 819, where a thin-walled nonmagnetic sleeve is used as the connecting part between the core and the valve seating body of a fuel injector. In terms of the design, this sleeve largely corresponds to the sleeve described in U.S. Pat. No. 4,946,107. The volume and the weight of the fuel injector can be reduced with the help of the tubular sleeves.
Published German Patent Application No. 195 47 406 also describes a fuel injector having an elongated, thin-walled, nonmagnetic sleeve which also has a bottom section in addition to its jacket section. The bottom section runs largely perpendicular to the otherwise axial extent of the sleeve along the longitudinal axis of the valve. A valve needle can move axially in a through-hole in the sleeve. A valve closing body fixedly connected to the valve needle works together with a valve seat face provided on a valve seating body, with the valve seating body pressed in the sleeve in direct or indirect contact with a bottom section of the sleeve by means of a perforated disk. To produce the finished valve, the sleeve is surrounded at least partially by an injection molded plastic sheathing.
The method according to the present invention for assembling a valve module of a fuel injector has the advantage that it can be carried out easily and inexpensively and therefore a reliable and secure assembly of the fuel injector is guaranteed. An external magnetic circuit part which conducts the magnetic flux can be attached very easily in the valve without using an additional joining method, so that bonding methods of joining need not be used in an advantageous manner. This eliminates all the disadvantages of methods that must be performed with heat, such as welding warpage. Assembly of the valve is also simplified inasmuch as no tools are needed for mounting the magnetic circuit part.